U.S. patent application number 16/952985 was filed with the patent office on 2021-03-18 for haloalkynyl dicobalt hexacarbonyl precursors for chemical vapor deposition of cobalt.
The applicant listed for this patent is ENTEGRIS, INC.. Invention is credited to Thomas H. BAUM, Seobong CHANG, Sangbum HAN, Bryan C. HENDRIX, Jae Eon PARK.
Application Number | 20210082708 16/952985 |
Document ID | / |
Family ID | 1000005251392 |
Filed Date | 2021-03-18 |
![](/patent/app/20210082708/US20210082708A1-20210318-C00001.png)
![](/patent/app/20210082708/US20210082708A1-20210318-C00002.png)
![](/patent/app/20210082708/US20210082708A1-20210318-D00001.png)
United States Patent
Application |
20210082708 |
Kind Code |
A1 |
HAN; Sangbum ; et
al. |
March 18, 2021 |
HALOALKYNYL DICOBALT HEXACARBONYL PRECURSORS FOR CHEMICAL VAPOR
DEPOSITION OF COBALT
Abstract
The present disclosure relates to a bridging asymmetric
haloalkynyl dicobalt hexacarbonyl precursors, and ultra high purity
versions thereof, methods of making, and methods of using these
bridging asymmetric haloalkynyl dicobalt hexacarbonyl precursors in
a vapor deposition process. One aspect of the disclosure relates to
an ultrahigh purity bridging asymmetric haloalkynyl dicobalt
hexacarbonyl precursor of the formula
Co.sub.2(CO).sub.6(R.sup.3C.ident.CR.sup.4), where R.sup.3 and
R.sup.4 are different organic moieties and R.sup.4 is more
electronegative or more electron withdrawing compared to
R.sup.3.
Inventors: |
HAN; Sangbum; (Norfolk,
VA) ; CHANG; Seobong; (Suwon, KR) ; HENDRIX;
Bryan C.; (Danbury, CT) ; PARK; Jae Eon;
(HwaSung-City, KR) ; BAUM; Thomas H.; (New
Fairfield, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ENTEGRIS, INC. |
Billerica |
MA |
US |
|
|
Family ID: |
1000005251392 |
Appl. No.: |
16/952985 |
Filed: |
November 19, 2020 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15819620 |
Nov 21, 2017 |
10872770 |
|
|
16952985 |
|
|
|
|
62425807 |
Nov 23, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 16/16 20130101;
C23C 16/06 20130101; C07F 15/06 20130101; C23C 16/18 20130101; H01L
21/28556 20130101 |
International
Class: |
H01L 21/285 20060101
H01L021/285; C23C 16/06 20060101 C23C016/06; C23C 16/16 20060101
C23C016/16; C07F 15/06 20060101 C07F015/06; C23C 16/18 20060101
C23C016/18 |
Claims
1-20. (cancaled)
21. A precursor or precursor composition for a vapor deposition
process of a cobalt film, the precursor or precursor composition
comprising: a bridging asymmetric haloalkynyl dicobalt hexacarbonyl
precursor of formula Co.sub.2(CO).sub.6(R.sup.3C.ident.CR.sup.4),
wherein R.sup.3 is H and R.sup.4 is --CF.sub.3.
22. The precursor or precursor composition of claim 21 having a
molecular purity of the bridging asymmetric haloalkynyl dicobalt
hexacarbonyl precursor of 99% or greater.
23. The precursor or precursor composition of claim 21, comprising
a solvent to form a solvent solution of said bridging asymmetric
haloalkynyl dicobalt hexacarbonyl precursor, said solvent solution
comprising in the range of from 0.05 M to 0.5 M bridging asymmetric
haloalkynyl dicobalt hexacarbonyl precursor.
24. The precursor or precursor composition of claim 23, wherein the
solvent comprises a hydrocarbon solvent.
25. The precursor or precursor composition of claim 21 packaged in
a container for subsequent use in a vapor deposition process.
26. The precursor or precursor composition of claim 21 sealed in an
ampoule configured to maintain an inert atmosphere and having
connections and valves to enable mounting to a gas manifold,
vaporizer, or bubbler.
27. A cobalt film deposition process comprising: volatilizing a
precursor or precursor composition according to claim 21 to form
precursor vapor; and, depositing the precursor vapor on a substrate
in a chamber to form a deposited cobalt film.
28. The process of claim 27, wherein the substrate is at a
temperature in a range of from 50.degree. C. to 250.degree. C.
during deposition.
29. The process of claim 27, wherein the precursor vapor is
deposited at a pressure in a in range of from 0.01 Torr to 100 Torr
in the chamber.
30. The process of claim 27, wherein the asymmetric haloalkynyl
dicobalt hexacarbonyl precursor has a temperature in the range of
from 18.degree. C. to 35.degree. C. during the volatization.
31. The process of claim 27, wherein the deposited cobalt film has
a resistivity measured at room temperature of 100 .mu..OMEGA.-cm or
less and the film has a thickness of 100 angstroms or less.
32. The process of claim 27, wherein the substrate is a
semiconductor product.
Description
FIELD OF THE INVENTION
[0001] The present disclosure relates to high purity, low
resistivity vapor deposited cobalt materials and to precursors and
processes for forming such high purity, low resistivity cobalt on
substrates. The cobalt material deposited by the precursors and
processes may be used in the manufacture of semiconductor products,
flat-panel displays, and solar panels.
BACKGROUND
[0002] Cobalt is finding increased use in semiconductor
manufacturing. For example cobalt disilicide has been progressively
displacing titanium silicide in microelectronic devices as feature
and linewidth dimensions decrease. Cobalt also is currently under
consideration as a conductive cap over copper lines or as part of
the barrier/adhesion layer liner for copper lines and contacts, as
an encapsulant material, as a seed material for electroless and
electroplating processes, and as a replacement material for copper
in wiring and interconnects of integrated circuits. Cobalt
additionally has elicited interest as a result of its magnetic
properties for data storage applications and its potential for
spintronics applications.
[0003] Interconnects are the backbone of integrated circuitry,
providing power and ground connections and distribution of clock
and other signals. Local interconnects comprise the lines that
connect gates and transistors, intermediate interconnects provide
wiring within functional blocks of integrated circuitry, and global
interconnects distribute clock and other signals and provide power
and ground connections for the entire integrated circuit.
Interconnects increasingly are a dominant factor in determining
system performance and power dissipation of integrated
circuits.
[0004] In the manufacture of integrated circuitry devices in which
copper is used as a metallization material, cobalt liners and back
end of the line (BEOL) interconnect caps have been developed for
protection of copper interconnects. Recently, it has been proposed
to replace the copper interconnect due to problems associated with
electron migration. Although various cobalt precursors have been
applied to such interconnect fabrication, the vapor deposited
cobalt thin films have been plagued by the presence of excess
residual carbon and oxygen impurities, which in turn has caused
such thin films to exhibit relatively low conductivity (resistivity
>50 microohm-cm).
[0005] There is continuing need for high purity, low resistivity
vapor deposited cobalt films and other deposited cobalt structures
that are used in forming interconnects and other metallization
features of integrated circuits.
[0006] The problem with using many bridging alkylalkynyl dicobalt
hexacarbonyl precursors like dicobalt hexacarbonyl butylacetylene
(CCTBA) for vapor deposition of cobalt thin films are their
viscosity and relatively low vapor pressure. CCTBA has a boiling
point of 52.degree. C. at 0.8 torr (106.7 Pa), and exists as a red
liquid at 25.degree. C., so that it requires additional heating for
the delivery of vapor to a deposition process. This additional
heating however accelerates the decomposition of the bridging
alkylalkynyl dicobalt hexacarbonyl precursor. Further, parts of the
bridging alkylalkynyl dicobalt hexacarbonyl precursors are
relatively stable during a vapor deposition process and so can
leave residual impurities like carbon in the deposited cobalt film
which increase the resistivity of the film.
[0007] It is an aim of the invention to address at least one of the
above-described problems or another problem associated with the
prior art.
SUMMARY
[0008] From a first aspect, the invention provides a precursor or
precursor composition for a vapor deposition process of a cobalt
film, the precursor or precursor composition comprising: a bridging
asymmetric haloalkynyl dicobalt hexacarbonyl precursor of formula
Co.sub.2(CO).sub.6(R.sup.3C.ident.CR.sup.4), wherein R.sup.3 and
R.sup.4 are different organic moieties and R.sup.4 is an electron
withdrawing organic moiety relative to R.sup.3.
[0009] The problem of low precursor volatility and high deposited
cobalt film resistivity can be solved by using the defined bridging
asymmetric haloalkynyl dicobalt hexacarbonyl precursors where the
di-cobalt precursors are functionalized with asymmetric alkyne
derivatives that include groups with high electronegativity on one
side of the alkyne. Such bridging asymmetric haloalkynyl dicobalt
hexacarbonyl precursors may have low viscosity compared to CCTBA
and can be used at room temperature in bubblers to provide vapor
deposited cobalt films with low electrical resistivity and lower
amounts of incorporated impurities like carbon.
[0010] At least one of R.sup.3 and R.sup.4 comprises one or more
halogen atoms, i.e. is a halo substituted organic moiety. The
bridging asymmetric haloalkynyl dicobalt hexacarbonyl precursors
may optionally have a structure where one of R.sup.3 and R.sup.4
comprises one or more halogen atoms and the other is free of
halogen atoms.
[0011] From a second aspect, the invention provides a precursor or
precursor composition for a vapor deposition process of a cobalt
film, the precursor or precursor composition comprising: a bridging
asymmetric haloalkynyl dicobalt hexacarbonyl precursor of formula
Co.sub.2(CO).sub.6(R.sup.3C.ident.CR.sup.4), wherein R.sup.3 and
R.sup.4 are different organic moieties, R.sup.4 comprises one or
more halogen atoms and R.sup.3 is free of halogen atoms.
[0012] The precursors may be adapted for use in a vapor deposition
process to deposit low resistivity cobalt material. In some
versions of the disclosure the molecular purity of the bridging
asymmetric haloalkynyl dicobalt hexacarbonyl precursor may be 99%
or greater.
[0013] In the bridging asymmetric haloalkynyl dicobalt hexacarbonyl
precursors, R.sup.3 may optionally be selected from the group
consisting of H, an alkyl moiety, and an aryl moiety. R.sup.4 may
suitably be a haloalkyl or haloaryl moiety, optionally a
fluoroalkyl moiety or a fluoroaryl moiety. In some versions,
R.sup.4 is selected from the group consisting of --CF.sub.3,
--C.sub.2F.sub.5, and --C.sub.6F.sub.5 moieties.
[0014] The bridging asymmetric haloalkynyl dicobalt hexacarbonyl
precursor composition may comprise one or more solvents to form a
solvent solution of the precursor. In the solvent solution
composition of the bridging asymmetric haloalkynyl dicobalt
hexacarbonyl precursor, the concentration of precursor may
optionally be from 0.05 moles precursor per liter of solvent (M) to
0.5 moles precursor per liter of solvent (M). In some versions of
the bridging asymmetric haloalkynyl dicobalt hexacarbonyl precursor
compositions, the amount of precursor in the solvent may be up to 5
wt %. In some versions of the precursor composition the solvent in
the solvent solution comprises an organic solvent, optionally a
hydrocarbon solvent.
[0015] The bridging asymmetric haloalkynyl dicobalt hexacarbonyl
precursor or precursor composition of the first aspect of the
invention may be used in a vapor deposition process to form cobalt
on a substrate. Low resistivities may advantageously be achieved.
The process comprises depositing the precursor vapor on a substrate
to form the cobalt on the substrate.
[0016] Thus, from a third aspect, the invention provides cobalt
deposition process, comprising: volatilizing a precursor or
precursor composition according to any aspect, version or
embodiment of the invention to form precursor vapor; and,
depositing the precursor vapor on a substrate in a chamber.
[0017] During the vapor deposition process, the substrate exposed
to the bridging asymmetric haloalkynyl dicobalt hexacarbonyl
precursor vapor may optionally be held at a temperature in a range
of from 50.degree. C. to 250.degree. C. during deposition. The
asymmetric haloalkynyl dicobalt hexacarbonyl precursor may suitably
be in a vessel that is held at room temperature, or may be held at
a temperature in a range of from 18.degree. C. to 35.degree. C.
during the volatization. The vapor deposition chamber during the
process may be at a deposition pressure in a range of from 0.01
Torr to 100 Torr. The cobalt film formed or deposited on the
substrate may optionally have a resistivity 100 .mu..OMEGA.-cm or
less when the film has a thickness of 100 angstroms or less.
[0018] The ability to volatilize the bridging asymmetric
haloalkynyl dicobalt hexacarbonyl precursor at low temperature, and
in some cases at room temperature, helps to prevent decomposition
of the bridging asymmetric haloalkynyl dicobalt hexacarbonyl
precursor which increases semiconductor manufacturing tool uptime
and reduces costs. Because the low temperature volatilization
reduces the decomposition of the bridging asymmetric haloalkynyl
dicobalt hexacarbonyl precursor it also reduces the need and cost
associated with the proper disposal of unusable bridging asymmetric
haloalkynyl dicobalt hexacarbonyl precursor. The bridging
asymmetric haloalkynyl dicobalt hexacarbonyl precursors can provide
high cobalt film growth rate even with room temperature
volatilization, and the resulting thin cobalt films can have low
resistivity.
[0019] From a fourth aspect, the invention provides a cobalt film
obtainable or obtained by the process according to the third aspect
of the invention.
[0020] From a firth aspect, the invention provides the use of a
bridging asymmetric haloalkynyl dicobalt hexacarbonyl precursor,
for example according to any aspect, version or embodiment herein,
in a vapor deposition process for the purpose of yielding high
purity deposited cobalt films, for example films that contain less
than 5 at % carbon and less than 3 at % oxygen.
[0021] From a sixth aspect, the invention provides the use of a
bridging asymmetric haloalkynyl dicobalt hexacarbonyl precursor,
for example according to any aspect, version or embodiment herein,
in a vapor deposition process for the purpose of yielding deposited
cobalt films containing less carbon and oxygen impurities than
films which would be obtained under comparable conditions with a
corresponding non-halogenated precursor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 illustrates the H.sup.1 NMR in C.sub.6H.sub.6 of
purified Co.sub.2(CO).sub.6(HC.ident.CCF.sub.3), which can be
abbreviated as CCFP.
DETAILED DESCRIPTION
[0023] The present disclosure relates to bridging asymmetric
haloalkynyl dicobalt hexacarbonyl precursors, and ultra high purity
versions thereof, methods of making, and methods of using these
bridging asymmetric haloalkynyl dicobalt hexacarbonyl precursors in
a vapor deposition process. One aspect of the disclosure relates to
an ultrahigh purity bridging asymmetric haloalkynyl dicobalt
hexacarbonyl precursor of the formula:
CO.sub.2(CO).sub.6(R.sup.3C.ident.CR.sup.4)
where R.sup.3 and R.sup.4 are different organic moieties and
R.sup.4 is more electronegative or more electron withdrawing
compared to R.sup.3.
[0024] The bridging asymmetric haloalkynyl dicobalt hexacarbonyl
precursors may optionally have a structure where one of R.sup.3 and
R.sup.4 comprises one or more halogen atoms and the other is free
of halogen atoms.
[0025] In some versions of the bridging asymmetric haloalkynyl
dicobalt hexacarbonyl precursor, R.sup.3 is selected from the group
consisting of H, an alkyl moiety, or an aryl moiety. R.sup.4 may,
for example, be a methyl moiety, an ethyl moiety, or aryl moiety
that includes one or more halogen atoms.
[0026] In some versions, the bridging asymmetric haloalkynyl
dicobalt hexacarbonyl precursors may have a boiling point in the
range of from 50.degree. C. to 100.degree. C.
[0027] In some versions the bridging asymmetric haloalkynyl
dicobalt hexacarbonyl precursors are liquid at room temperature.
The precursors may have a low enough viscosity that they can be
used efficiently in a bubbler with the liquid being at or near room
temperature.
[0028] The bridging asymmetric haloalkynyl dicobalt hexacarbonyl
precursors in versions of the disclosure include those of formula
Co.sub.2(CO).sub.6(R.sup.3C.ident.CR.sup.4) where R.sup.3 is
selected from the group consisting of H, an alkyl moiety, or an
aryl moiety and R.sup.4 is a methyl moiety, an ethyl moiety, or
aryl moiety that includes one or more halogen atoms and that yield
deposited cobalt films that contain less carbon and oxygen
impurities compared to bridging symmetric alkyne dicobalt
hexacarbonyl precursors of formula Co.sub.2(CO).sub.6(RC.ident.CR)
where R is absent halogen atoms.
[0029] According to still another aspect of the disclosure, the
bridging asymmetric haloalkynyl dicobalt hexacarbonyl precursors
may be made by a method comprising reacting dicobalt octacarbonyl
with an alkyne to give a bridging alkyne dicobalt hexacarbonyl as
illustrated in reaction (1) below.
##STR00001##
[0030] The Co.sub.2(CO).sub.6(R.sup.1C.ident.CR.sup.2) compound can
undergo an exchange reaction with asymmetric haloalkynes of formula
R.sup.3C.ident.CR.sup.4 (where R.sup.4 as described herein includes
one or more halogen atoms and R.sup.4 is more electron withdrawing
or electronegative than R.sup.3) to yield a bridging asymmetric
haloalkynyl dicobalt hexacarbonyl precursor of formula
Co.sub.2(CO).sub.6(R.sup.3C.ident.CR.sup.4). This exchange reaction
is illustrated in reaction (2) below.
##STR00002##
[0031] The resulting bridging asymmetric haloalkynyl dicobalt
hexacarbonyl precursor of formula
Co.sub.2(CO).sub.6(R.sup.3C.ident.CR.sup.4) can be purified to
remove any residual (R.sup.1C.ident.CR.sup.2), greases, and other
impurities.
[0032] Another aspect of the disclosure relates to a method
purifying an ultrahigh purity bridging asymmetric haloalkynyl
dicobalt hexacarbonyl precursor of the formula:
Co.sub.2(CO).sub.6(R.sup.3C.ident.CR.sup.4),
for example a asymmetric haloalkynyl dicobalt hexacarbonyl
precursor according to any aspect, version or embodiment of the
invention, where the bridging asymmetric haloalkynyl dicobalt
hexacarbonyl precursor compound is chromatagraphically separated
from reaction product impurities by passage through an affinity
medium by elution with a solvent to recover an
Co.sub.2(CO).sub.6(R.sup.3C.ident.CR.sup.4) eluate and
concentrating the Co.sub.2(CO).sub.6(R.sup.3C.ident.CR.sup.4)
eluate to recover a concentrate as the ultrahigh purity bridging
asymmetric haloalkynyl dicobalt hexacarbonyl precursor.
[0033] The precursor resulting from the purification is at an
ultrahigh purity of 99.0 wt %, 99.5 wt %, 99.95 wt %, 99.99 wt % or
higher. Purity may be taken as molecular purity of the bridging
asymmetric haloalkynyl dicobalt hexacarbonyl precursor.
Alternatively, purity may be taken as elemental purity of Co. In
some compositions the molecular or elemental purity may be from
99.9 wt % to 99.9999 wt % molecular purity of the bridging
asymmetric haloalkynyl dicobalt hexacarbonyl precursor. For
example, a sample of the bridging asymmetric haloalkynyl dicobalt
hexacarbonyl precursor following purification may be 99.999 wt %
molecular or elemental purity of bridging asymmetric haloalkynyl
dicobalt hexacarbonyl and less than 0.001 wt % impurity. Higher
molecular or elemental purity of the bridging asymmetric
haloalkynyl dicobalt hexacarbonyl precursor in a vaporization
ampoule or bubbler provides higher purity cobalt films on the
substrate following vapor deposition.
[0034] The precursor asymmetric haloalkynyl dicobalt hexacarbonyl
precursor may be employed directly for vapour deposition, or may
form part of a precursor composition, for example when combined
with a solvent. The bridging asymmetric haloalkynyl dicobalt
hexacarbonyl precursor or composition may be packaged in a suitable
container for subsequent use in a vapor deposition process. For
example, the precursor, or a composition comprising the precursor,
may be sealed in an ampoule that has connections and valves to
maintain an inert atmosphere above the precursor and enable
mounting to a gas manifold, vaporizer, or bubbler.
[0035] The viscosity of neat bridging asymmetric haloalkynyl
dicobalt hexacarbonyl precursors or solutions of them with a
solvent may suitably be in the range of 1 centipoise (cP) to 40
(cP). Compositions of bridging asymmetric haloalkynyl dicobalt
hexacarbonyl with viscosities in this range may be used in bubblers
or vaporizers directly to feed a vapor deposition process.
Solutions of bridging asymmetric haloalkynyl dicobalt hexacarbonyl
precursors may suitably include those that comprise from 5 wt % to
95 wt % solvent. In some versions, solutions of bridging asymmetric
haloalkynyl dicobalt hexacarbonyl precursors include from 0.05
moles precursor per liter of solvent (M) to 0.5 moles precursor per
liter of solvent (M). Higher concentrations than 0.5 M precursor
may be used, with the benefit being less vapor to dispose of and
less chance of incorporation of solvent impurity in the deposited
film. In some versions of solutions the solvent may be an organic
solvent, optionally a hydrocarbon solvent.
[0036] In yet another aspect, the disclosure relates to a cobalt
deposition process, comprising: volatilizing the bridging
asymmetric haloalkynyl dicobalt hexacarbonyl precursor or precursor
composition to form precursor vapor; and, depositing the precursor
vapor on a substrate in a chamber. In some versions, the disclosure
relates to a cobalt deposition process, comprising the acts or
steps of volatilizing the bridging asymmetric haloalkynyl dicobalt
hexacarbonyl precursor to form a bridging asymmetric haloalkynyl
dicobalt hexacarbonyl precursor vapor; and contacting the bridging
asymmetric haloalkynyl dicobalt hexacarbonyl precursor vapor with a
substrate under vapor deposition conditions effective for
depositing on the substrate (i) high purity, low resistivity cobalt
or (ii) cobalt that is annealable by thermal annealing to form high
purity, low resistivity cobalt.
[0037] Where the vapor deposition process is a chemical vapor
deposition process (CVD), the CVD reactor conditions may optionally
include a substrate process temperature in the range of from
50.degree. C. to 250.degree. C.
[0038] The vapor deposition process may optionally be performed at
a reaction chamber pressure in the range of from 0.01 Torr to 100
Torr. Suitably an intert carrier inert gas flow, for example in the
range of from 10 standard cubic centimeters per minute (sccm) to
1000sccm, may be provided. Optionally, a flow of reactant or
reactive gas, for example H.sub.2 , may be provided, optionally at
a flow in the range of from 10 sccm to 5000 sccm.
[0039] Reactive gases that may be used during vapor deposition of
the bridging asymmetric haloalkynyl dicobalt hexacarbonyl
precursors include hydrogen (e.g., H.sub.2 or atomic-H), nitrogen
(e.g., N or atomic-N), ammonia (NH.sub.3), a hydrogen and ammonia
mixture (H.sub.2/NH.sub.3), hydrazine (N.sub.2H.sub.4), helium,
argon, derivatives thereof, plasmas thereof, or combinations
thereof. Inert gases like nitrogen, argon, and helium may be used
as carrier or diluent gas.
[0040] The process may pulse the cobalt precursor with a constant
flow of reactant gas or the process may pulse the cobalt precursor
alternatively with the flow of reactant gas. In the latter case, a
purge of inert gas may be inserted after the cobalt precursor flow
and before the reactant gas flow and/or after the reactant gas flow
and before the cobalt precursor flow. Under the condition of
reactant gas flow without cobalt precursor flow, a plasma may also
be lit in the gas to additionally activate the reactant gas.
[0041] In some versions, the bridging asymmetric haloalkynyl
dicobalt hexacarbonyl precursors may have a boiling point in the
range of from 50.degree. C. to 100.degree. C. This may allow them
to exhibit sufficient vapor pressure near room temperature
(18.degree. C. to 35.degree. C.) that cobalt films may be grown at
rates of from 20 A per minute to 35 A per minute. In some versions,
the asymmetric haloalkynyl dicobalt hexacarbonyl precursor may he
held at a temperature in a range of from 18.degree. C. to
35.degree. C. in an ampoule or bubbler during the volatization to
produce precursor vapor for the deposition process.
[0042] The bridging asymmetric haloalkynyl dicobalt hexacarbonyl
precursor may be volatilized from the neat material, or by passing
an inert gas through the neat bridging asymmetric haloalkynyl
dicobalt hexacarbonyl precursor using a bubbler. Solvent solutions
of the bridging asymmetric haloalkynyl dicobalt hexacarbonyl
precursor may also be volatilized using a bubbler or vaporizer. The
bridging asymmetric haloalkynyl dicobalt hexacarbonyl precursor may
be held at a temperature that provides sufficient vapor to the
process. In some versions of a deposition process utilizing a
bridging asymmetric haloalkynyl dicobalt hexacarbonyl precursor,
the temperature of the precursor or a solution thereof is near room
temperature or in the range of from 18.degree. C. to 35.degree. C.
In some other versions of the deposition process the temperature of
the bridging asymmetric haloalkynyl dicobalt hexacarbonyl precursor
is kept below the decomposition or boiling point of the bridging
asymmetric haloalkynyl dicobalt hexacarbonyl precursor. Low
temperatures reduce the decomposition of the precursor in the
ampoule and may reduce overall costs by decreasing waste.
[0043] The cobalt may be deposited as a film. Cobalt films prepared
by vapor deposition of the bridging asymmetric haloalkynyl dicobalt
hexacarbonyl precursors may be high purity films. The term "high
purity" refers to cobalt films containing less than 5 at% carbon
and less than 3 at% oxygen in the cobalt film. High purity films
may also be characterized by their electrical resistivity which in
versions of the disclosure are measured at room temperature (RT,
20.degree. C.-23.degree. C.). Versions of cobalt films prepared by
vapor deposition of the bridging asymmetric haloalkynyl dicobalt
hexacarbonyl precursor include those "low resistivity" cobalt films
with a measured four point electrical resistivity that is less than
100 .mu..OMEGA.-cm for a 100 .ANG. or thinner cobalt film. In some
versions the cobalt films prepared by vapor deposition of the
bridging asymmetric haloalkynyl dicobalt hexacarbonyl precursor
include those "low resistivity" cobalt films that have a measured
four point electrical resistivity that is 12 .mu..OMEGA.-cm to 30
.mu..OMEGA.-cm for a 300 .ANG. or thinner cobalt film. Low
resistivity films are beneficial for interconnects because they
require less power and generate less heat than higher resistivity
films.
[0044] The term "organic moiety" as used herein refers to hydrogen
or moieties containing carbon. Such moieties may be optionally
substituted as defined herein, for example with one or more halo
substituents. Of course, moieties may also be unsubstituted. The
term "moiety" is well understood in the art. Other terms such as
"radical" or "group" are sometimes used to mean "moiety".
[0045] The term "electron-withdrawing" as applied to a substituent
or moiety refers to the ability of a substituent or moiety to draw
electrons to itself, e.g. more so than a hydrogen atom would if it
occupied the same position in the molecule. This term is well
understood and is discussed in Advanced Organic Chemistry, by J.
March, 3th Ed. John Wiley and Sons, New York, N.Y. pp. 16-18
(1985). Non-limiting examples of electron withdrawing substituents
include halo, especially fluoro, chloro, bromo, and iodo. Electron
withdrawing moieties may include haloalkyl and haloaryl
moieties.
[0046] The term "alkyl," as used herein, alone or in combination,
refers to a straight-chain, branched, or cyclic alkyl moiety, or a
moiety consisting of any combination of straight, branched, and/or
cyclic moieties, which is a saturated aliphatic hydrocarbon moiety,
suitably containing from 1-10 carbon atoms. In some versions, alkyl
moieties comprise 1-6 carbon atoms. The term "alkyl moieties" is
used in its broadest sense. Alkyl moieties may be optionally
substituted as defined herein. Examples of alkyl moieties include
methyl, ethyl, n-propyl, isopropyl, cyclopropyl, cyclopropylmethyl,
n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, pentyl,
neopentyl, iso-amyl, hexyl, cyclohexyl, and the like.
[0047] The term "asymmetric haloalkynyl" refers to an organic group
that has an acetylenic bond between first and second acytelenic
carbons, with different moieties bonded to the first and second
acytelenic carbons and a haloalkyl or a haloaryl moiety bonded to
one or both acytelenic carbons. In some versions, the term
"asymmetric haloalkynyl" refers to an organic group that has an
acetylenic bond with an H, alkyl or aryl moiety bonded to the first
acetylenic carbon and a haloalkyl or a haloaryl moiety bonded to
the second acetylenic carbon. In some versions a haloalkynyl group
may contain from 2 to 12 carbon atoms. The asymmetric haloalkynyl
group is a bridging ligand in the dicobalt hexacarbonyl precursors.
Non-limiting examples of asymmetric haloalkynyl bridging groups may
include 3,3,3-trifluoropropyne and pentafluorophenyl acetylene.
[0048] The term "haloalkyl," as used herein, alone or in
combination, refers to an alkyl moiety where one or more hydrogens
are replaced with a halogen. Examples can include monohaloalkyl,
dihaloalkyl and polyhaloalkyl moieties. A monohaloalkyl moiety, for
one example, may have either an iodo, bromo, chloro or fluoro atom
within the moiety. Dihalo and polyhaloalkyl moieties may have two
or more of the same halo atoms or a combination of different halo
moieties. Examples of haloalkyl moieties can include fluoromethyl,
difluoromethyl, trifluoromethyl, chloromethyl, dichloromethyl,
trichloromethyl, trichloroethyl, pentafluoroethyl,
heptafluoropropyl, difluorochloromethyl, dichlorofluoromethyl,
difluoroethyl, difluoropropyl, dichloroethyl and dichloropropyl. In
some versions the alkyl moiety has all of the hydrogen atoms
replaced by halogen atoms; the halogen atoms may be the same or
different. Some versions of haloalkyl moieties include
trifluoromethyl (--CF.sub.3), and pentafluoroethyl
(--C.sub.2F.sub.5).
[0049] Aromatic or aryl moieties include unsaturated, cyclic
hydrocarbons having alternate single and double bonds. Benzene is a
typical aromatic compound. The term haloaryl refers to an aryl
moiety having one or more hydrogen atoms replaced by a halogen atom
or one or more halogen atoms. When there are plurality of halogen
atoms, the halogen atoms may be the same or different. In some
versions the aryl moiety has all of the hydrogen atoms replaced by
halogen atoms; the halogen atoms may be the same or different. In
one version the aryl moiety is the pentafluorophenyl
(--C.sub.6F.sub.5).
[0050] Various non-limiting embodiments of the invention are
described in the following Examples.
[0051] Example 1. This example illustrates the deposition of a
cobalt film that was made by volatilizing a composition comprising
a bridging asymmetric haloalkynyl dicobalt hexacarbonyl precursor
and depositing the precursor vapor on a SiO.sub.2 substrate in a
chamber.
[0052] The bridging asymmetric haloalkynyl dicobalt hexacarbonyl
precursor in this example has a formula
Co.sub.2(CO).sub.6(HC.ident.CCF.sub.3) which can be abbreviated as
CCFP. In this dicobalt complex the different organic moieties
bonded to the acetylenic carbon are --H and --CF.sub.3, and
--CF.sub.3 is an electron withdrawing organic group relative to
--H. An .sup.1H NMR of the Co.sub.2(CO).sub.6(HC.ident.CCF.sub.3)
precursor is shown in FIG. 1.
[0053] A comparative cobalt film was deposited on SiO.sub.2 from
dicobalt hexacarbonyl butylacetylene (CCTBA). The conditions and
outcomes of these two deposition runs are summarized in Table 1
below.
TABLE-US-00001 TABLE 1 Conditions/Results CCTBA CCFP Substrate
SiO.sub.2 SiO.sub.2 Substrate Temp. 159.degree. C. 150.degree. C.
Carrier gas and flow Ar (500 seem) Ar (100 seem) H.sub.2 (1000
seem) H.sub.2 (1000 seem) Deposition Chamber pressure 29 Torr 58
Torr Bubbler Temperature 40.degree. C. Room temp ~23.degree. C.
Line temperature from bubbler to chamber Bubbler temp, +10.degree.
C. Bubbler temp, +10.degree. C. Growth Rate determined by X-ray
fluorescence 17 .ANG./min 27 .ANG./min R.sub.s four-probe @RT 29.65
micro-Ohm cm 26.34 micro-Ohm cm
[0054] The results of this example show that the bridging
asymmetric haloalkynyl dicobalt hexacarbonyl of formula
Co.sub.2(CO).sub.6(HC.ident.CCF.sub.3) was able to be adapted to
vapor deposit cobalt thin films on a substrate. The deposition rate
was in the range of about 25 .ANG. per minute to 30 .ANG. per
minute. The bubbler containing the CCFP was held at about room
temperature. The resulting film from the CCFP precursor had a low
resistivity of 26.34 micro-Ohmcm measured at room temperature (RT,
20.degree. C.-23.degree. C.) compared to the film that was
deposited under similar conditions using CCTBA which had a
resistivity of 29.65 micro-Ohmcm.
[0055] Example 2. This example illustrates the vapor deposition of
cobalt films on a substrate under various process conditions using
the bridging asymmetric haloalkynyl dicobalt hexacarbonyl of
formula Co.sub.2(CO).sub.6(HC.ident.CCF.sub.3). The bubbler
containing the Co.sub.2(CO).sub.6(HC.ident.CCF.sub.3) was at room
temperature and a flow of Argon gas at 100 sccm was used. Hydrogen
gas at a flow of 1000 sccm was used as a reactive gas for the
cobalt deposition. The results of the experiment are summarized in
Table 2 below.
TABLE-US-00002 TABLE 2 Chamber Chamber Deposition Film Sheet
Resistivity Temp Pressure Time Thickness resistance (4-probe)
Sample (.degree. C.) (Torr) (sec) (.ANG.) (ohms/sq) (.mu..OMEGA.
cm) @ RT A 130 10 3000 261.3 22.78 59.45 B 170 50 600 479.7 6.21
29.75 C 150 30 1080 549.7 6.27 34.47
[0056] The results of this example show that low resistivity cobalt
films of thickness ranging from 260 .ANG. to 550 .ANG. could be
made using the bridging asymmetric haloalkynyl dicobalt
hexacarbonyl precursor of formula
Co.sub.2(CO).sub.6(HC.ident.CCF.sub.3) under a variety of chamber
and process conditions. The cobalt films with the thicknesses in
this range had a resistivity measured by the 4-point probe that
ranged from 29.75 micro-ohmcm to 59.45 micro-ohmcm.
[0057] The present disclosure provides high purity bridging
asymmetric haloalkynyl dicobalt hexacarbonyl precursors of formula
Co.sub.2(CO).sub.6(R.sup.3C.ident.CR.sup.4) that can be adapted to
vapor deposit low resistivity (<100 .mu..OMEGA.-cm) cobalt films
and products including these films. These low resistivity cobalt
films may be deposited on various substrates and used in the
manufacture of semiconductor memory chips, application specific
integrated circuits (ASICs), microprocessors, flat-panel displays,
and solar panels.
[0058] While various compositions and methods are described, it is
to be understood that this invention is not limited to the
particular molecules, compositions, designs, methodologies or
protocols described, as these may vary. It is also to be understood
that the terminology used in the description is for the purpose of
describing the particular versions or embodiments only, and is not
intended to limit the scope of the present invention which will be
limited only by the appended claims.
[0059] It must also be noted that as used herein and in the
appended claims, the singular forms "a", "an", and "the" include
plural reference unless the context clearly dictates otherwise.
Thus, for example, reference to a "halo atom" is a reference to one
or more halo atoms and equivalents thereof known to those skilled
in the art, and so forth. Unless defined otherwise, all technical
and scientific terms used herein have the same meanings as commonly
understood by one of ordinary skill in the art. Methods and
materials similar or equivalent to those described herein can be
used in the practice or testing of embodiments of the present
invention. All publications mentioned herein are incorporated by
reference in their entirety. Nothing herein is to be construed as
an admission that the invention is not entitled to antedate such
disclosure by virtue of prior invention. "Optional" or "optionally"
means that the subsequently described event or circumstance may or
may not occur, and that the description includes instances where
the event occurs and instances where it does not. All numeric
values herein can be modified by the term "about," whether or not
explicitly indicated. The term "about" generally refers to a range
of numbers that one of skill in the art would consider equivalent
to the recited value (i.e., having the same function or result). In
some embodiments the term "about" refers to .+-.10% of the stated
value, in other embodiments the term "about" refers to .+-.2% of
the stated value. While compositions and methods are described in
terms of "comprising" various components or steps (interpreted as
meaning "including, but not limited to"), the compositions and
methods can also "consist essentially of" or "consist of" the
various components and steps, such terminology should be
interpreted as defining essentially closed or closed member
groups.
[0060] Although the invention has been shown and described with
respect to one or more implementations, equivalent alterations and
modifications will occur to others skilled in the art based upon a
reading and understanding of this specification and the annexed
drawings. The invention includes all such modifications and
alterations and is limited only by the scope of the following
claims. In addition, while a particular feature or aspect of the
invention may have been disclosed with respect to only one of
several implementations, such feature or aspect may be combined
with one or more other features or aspects of the other
implementations as may be desired and advantageous for any given or
particular application. Furthermore, to the extent that the terms
"includes", "having", "has", "with", or variants thereof are used
in either the detailed description or the claims, such terms are
intended to be inclusive in a manner similar to the term
"comprising." Also, the term "exemplary" is merely meant to mean an
example, rather than the best. It is also to be appreciated that
features, layers and/or elements depicted herein are illustrated
with particular dimensions and/or orientations relative to one
another for purposes of simplicity and ease of understanding, and
that the actual dimensions and/or orientations may differ
substantially from that illustrated herein.
* * * * *